Raw Crystal Buying Guide: How to Spot Authentic Gemstones

The raw crystal market has exploded in recent years, and with it, a flood of imitations. Glass sold as quartz. Plastic sold as amber. Lab-grown sapphire sold as natural. This guide gives you five practical tests to identify authentic gemstones.

Test one: temperature. Natural gemstones are dense and take time to warm in your hand. Glass and plastic are poor insulators and warm almost instantly. Hold the stone for ten seconds; if it already feels warm, be suspicious.

Test two: hardness. Each mineral has a Mohs hardness rating. Quartz (amethyst, citrine, clear quartz) is a 7, meaning it will scratch glass (5.5) but not steel (6.5). A real amethyst will leave a scratch on a glass surface; glass imitations will not. Carry a piece of glass or a steel knife for field testing.

Test three: inclusions. Natural gemstones almost always have internal features: tiny crystals, veils, color zoning, or what emerald dealers call jardin (garden). Flawless stones at low prices are almost always synthetic or glass. Look for these natural fingerprints under a magnifying glass or phone camera macro lens.

Test four: weight. Gemstones are denser than glass. A real garnet feels noticeably heavier than a glass imitation of the same size. This is called specific gravity. Garnet is 3.5-4.3, quartz is 2.65, and glass is around 2.5. If a stone feels suspiciously light, it is probably glass.

Test five: color. Natural color is rarely uniform. Real amethyst has subtle color zoning, lighter at the edges. Real aquamarine has a soft, sea-glass quality, not the electric blue of dyed topaz. Real peridot is always yellowish-green, never blue or teal. Study reference photos of natural stones before shopping.

Beyond these tests, always ask the seller three questions: What is the Mohs hardness? What is the country of origin? Can you provide a certificate? A reputable seller will answer without hesitation. If they dodge these questions, walk away.

At Lustre, every stone we sell comes with its mineral name, hardness rating, and country of origin. We do not sell glass, plastic, or lab-grown stones. Our raw crystal pieces preserve the natural geometry of each stone, exactly as it emerged from the Earth.